Bermuda Aviation Services Ltd (BAS) fell 4.7 percent in Bermuda Stock Exchange (BSX) trading yesterday.BAS slipped 20 cents to close on $4.05 as 1,500 shares traded.Butterfield Bank was the only other domestic board issuer to trade and remained on $1.25 as 26,200 of its shares changed hands.The Royal Gazette/BSX Index fell 0.87 points, or 0.08 percent, to close on 1,120.94.Volume was 27,700 shares and turnover was $38,325.